HR: 1340h
AN: OS33A-1002    [Abstracts]
TI: Lobe Shifting in the Gulf of Papua: Internal or External Forcing?
AU: * Johnstone, E A
EM: eajohnst@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. GRD 0244, La Jolla, Ca 92037, United States
AU: Driscoll, N W
EM: ndriscoll@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. GRD 0244, La Jolla, Ca 92037, United States
AU: Slingerland, R
EM: sling@geosc.psu.edu
AF: The Pennsylvania State University, 513A Deike, Dept of Geosciences, University Park, PA 16802, United States
AU: Milliman, J D
EM: milliman@vims.edu
AF: College of William and Mary, School of Marine Science, 1208 Greate Road, Gloucester Pt., VA 23062, United States
AU: Babcock, J
EM: jbabcock@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. GRD 0244, La Jolla, Ca 92037, United States
AB: Recently acquired CHIRP data from the Gulf of Papua (GoP) reveals that the modern clinoform is inherently three- dimensional across a variety of scales. Three depositional lobes are identified in the mid-shelf region of the GoP; a central lobe that is downlapped by younger northern and southern lobes. While the depocenter shift and infilling of available accommodation within the central lobe appears to be predominantly controlled by depositional processes and stacking patterns (autocyclic forces), the marked shift in deposition away from the central lobe to the northern and southern lobes (~60-80 km) is difficult to explain by depositional processes alone. The northern and southern lobes downlap onto the central lobe with no evidence of interfingering, which suggests an abrupt shift in the loci of deposition away from the central lobe. Radiocarbon dates from the youngest units in the central lobe suggest this shift occurred after 2 ka and thus it is difficult to invoke eustatic sea level fluctuations to explain this marked shift in deposition. Sediment rerouting or oceanographic changes may account for this dramatic shift in the depositional lobes. High-resolution mapping of the three dimensional architecture of shelf building clinothems has provided new insight into sediment dispersal systems that is the critical first step to determine whether GoP lobe switching is a stochastic (autocyclic) or externally driven (allocyclic) process.
DE: 4243 Marginal and semi-enclosed seas
DE: 9355 Pacific Ocean
DE: 9604 Cenozoic
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting